Optical fiber cables are becoming increasingly more common for use in transmitting high speed data in communication networks. These optical fibers must be terminated to equipment (e.g., optical transmitters such as lasers and LEDs or optical receivers, such as photodiodes, etc.) or other fibers. This is done through the use of ferrules and connectors at the ends of optical fiber cables that join with mating connectors on the termination equipment. As is well known, these connectors comprise ferrules within which the individual optical fibers are positioned very precisely so that they will align with the light receiving or light emitting face of the component to which it is being connected (or to the corresponding fibers of another optical cable). Proper alignment is important to minimize insertion loss so that the maximum amount of light can be transferred from the fiber to the receiving device or from the emitting device to the fiber. This will maximize the number of connectors that can be used in a link or maximize the length of fiber that can be supported.
Accordingly, when an optical cable is terminated with a connector, it is common to measure and test the alignment of the fibers in the connector to assure that they meet certain tolerances (i.e., that all the fibers at the front end of the connector where it will connect to another mating connector, are where they should be relative to the connector body).
There are many standardized form factors for optical connectors, including FC, ST, SC, and MT. The MT form factor is one form factor that is designed to connect cables bearing multiple fibers. For instance, MT connectors are presently available for connecting cables bearing up to 72 individual optical fibers (up to 6 rows of 12 fibers each).
MT type connectors have almost become the de facto type of connector used with multi-fiber interconnects.
There are presently several different types of systems available for measuring fiber alignment in optical connectors, including MT style connectors. Present system, apparatus, and methods for measuring the alignments of fibers in connectors have many disadvantages, such as, long test times, limited accuracy and relatively high equipment costs.
Probably the highest quality systems in terms of accuracy and speed of measurement are optical microscopes with CCD cameras. These systems have resolutions of about 1 micron and require about 10 minutes to measure the positions of all fibers in a 72 fiber connector. Such systems also are relatively expensive. Furthermore, if it is desired to assure the quality of the cable and connector assembly, a separate, subsequent performance test, such as an insertion loss test, is still required.